A 14-year-old girl presents with sudden onset right-sided lo…
A 14-year-old girl presents with sudden onset right-sided lower abdominal pain that began earlier today. She reports that the pain is sharp, lasted about 3-4 hours, and is now improving. She denies fever, vomiting, diarrhea, urinary symptoms, or vaginal discharge. Her periods are regular, and she is on day 13 of her cycle. She denies sexual activity. Vital signs are normal. Abdominal exam reveals mild right lower quadrant tenderness without rebounding or guarding. Pelvic ultrasound is normal with no ovarian enlargement or free fluid. Which of the following is the most likely diagnosis?